/**
 * Copyright 2014-2020 [fisco-dev]
 *
 * <p>Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of the License at
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>Unless required by applicable law or agreed to in writing, software distributed under the
 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.fisco.bcos.sdk.v3.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.LinkedList;
import java.util.List;

/** String utility functions. */
public class StringUtils {

    private StringUtils() {}

    public static String toCsv(List<String> src) {
        return join(src, ", ");
    }

    public static String join(List<String> src, String delimiter) {
        return src == null ? null : String.join(delimiter, src.toArray(new String[0]));
    }

    public static String capitaliseFirstLetter(String string) {
        if (string == null || string.length() == 0) {
            return string;
        } else {
            return string.substring(0, 1).toUpperCase() + string.substring(1);
        }
    }

    public static String lowercaseFirstLetter(String string) {
        if (string == null || string.length() == 0) {
            return string;
        } else {
            return string.substring(0, 1).toLowerCase() + string.substring(1);
        }
    }

    public static String zeros(int n) {
        return repeat('0', n);
    }

    public static String repeat(char value, int n) {
        return new String(new char[n]).replace("\0", String.valueOf(value));
    }

    public static boolean isEmpty(String s) {
        return s == null || s.isEmpty();
    }

    public static String fromUTF8ByteArray(byte[] bytes) {
        int i = 0;
        int length = 0;

        while (i < bytes.length) {
            length++;
            if ((bytes[i] & 0xf0) == 0xf0) {
                // surrogate pair
                length++;
                i += 4;
            } else if ((bytes[i] & 0xe0) == 0xe0) {
                i += 3;
            } else if ((bytes[i] & 0xc0) == 0xc0) {
                i += 2;
            } else {
                i += 1;
            }
        }

        char[] cs = new char[length];

        i = 0;
        length = 0;

        while (i < bytes.length) {
            char ch;

            if ((bytes[i] & 0xf0) == 0xf0) {
                int codePoint =
                        ((bytes[i] & 0x03) << 18)
                                | ((bytes[i + 1] & 0x3F) << 12)
                                | ((bytes[i + 2] & 0x3F) << 6)
                                | (bytes[i + 3] & 0x3F);
                int U = codePoint - 0x10000;
                char W1 = (char) (0xD800 | (U >> 10));
                char W2 = (char) (0xDC00 | (U & 0x3FF));
                cs[length++] = W1;
                ch = W2;
                i += 4;
            } else if ((bytes[i] & 0xe0) == 0xe0) {
                ch =
                        (char)
                                (((bytes[i] & 0x0f) << 12)
                                        | ((bytes[i + 1] & 0x3f) << 6)
                                        | (bytes[i + 2] & 0x3f));
                i += 3;
            } else if ((bytes[i] & 0xd0) == 0xd0 || (bytes[i] & 0xc0) == 0xc0) {
                ch = (char) (((bytes[i] & 0x1f) << 6) | (bytes[i + 1] & 0x3f));
                i += 2;
            } else {
                ch = (char) (bytes[i] & 0xff);
                i += 1;
            }

            cs[length++] = ch;
        }

        return new String(cs);
    }

    public static byte[] toUTF8ByteArray(String string) {
        return toUTF8ByteArray(string.toCharArray());
    }

    public static byte[] toUTF8ByteArray(char[] string) {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();

        try {
            toUTF8ByteArray(string, bOut);
        } catch (IOException e) {
            throw new IllegalStateException("cannot encode string to byte array!");
        }

        return bOut.toByteArray();
    }

    public static void toUTF8ByteArray(char[] string, OutputStream sOut) throws IOException {
        int i = 0;

        while (i < string.length) {
            char ch = string[i];

            if (ch < 0x0080) {
                sOut.write(ch);
            } else if (ch < 0x0800) {
                sOut.write(0xc0 | (ch >> 6));
                sOut.write(0x80 | (ch & 0x3f));
            }
            // surrogate pair
            else if (ch >= 0xD800 && ch <= 0xDFFF) {
                // in error - can only happen, if the Java String class has a
                // bug.
                if (i + 1 >= string.length) {
                    throw new IllegalStateException("invalid UTF-16 codepoint");
                }
                char W1 = ch;
                ch = string[++i];
                char W2 = ch;
                // in error - can only happen, if the Java String class has a
                // bug.
                if (W1 > 0xDBFF) {
                    throw new IllegalStateException("invalid UTF-16 codepoint");
                }
                int codePoint = (((W1 & 0x03FF) << 10) | (W2 & 0x03FF)) + 0x10000;
                sOut.write(0xf0 | (codePoint >> 18));
                sOut.write(0x80 | ((codePoint >> 12) & 0x3F));
                sOut.write(0x80 | ((codePoint >> 6) & 0x3F));
                sOut.write(0x80 | (codePoint & 0x3F));
            } else {
                sOut.write(0xe0 | (ch >> 12));
                sOut.write(0x80 | ((ch >> 6) & 0x3F));
                sOut.write(0x80 | (ch & 0x3F));
            }

            i++;
        }
    }

    /**
     * A locale independent version of toUpperCase.
     *
     * @param string input to be converted
     * @return a US Ascii uppercase version
     */
    public static String toUpperCase(String string) {
        boolean changed = false;
        char[] chars = string.toCharArray();

        for (int i = 0; i != chars.length; i++) {
            char ch = chars[i];
            if ('a' <= ch && 'z' >= ch) {
                changed = true;
                chars[i] = (char) (ch - 'a' + 'A');
            }
        }

        if (changed) {
            return new String(chars);
        }

        return string;
    }

    /**
     * A locale independent version of toLowerCase.
     *
     * @param string input to be converted
     * @return a US ASCII lowercase version
     */
    public static String toLowerCase(String string) {
        boolean changed = false;
        char[] chars = string.toCharArray();

        for (int i = 0; i != chars.length; i++) {
            char ch = chars[i];
            if ('A' <= ch && 'Z' >= ch) {
                changed = true;
                chars[i] = (char) (ch - 'A' + 'a');
            }
        }

        if (changed) {
            return new String(chars);
        }

        return string;
    }

    public static byte[] toByteArray(char[] chars) {
        byte[] bytes = new byte[chars.length];

        for (int i = 0; i != bytes.length; i++) {
            bytes[i] = (byte) chars[i];
        }

        return bytes;
    }

    public static byte[] toByteArray(String string) {
        byte[] bytes = new byte[string.length()];

        for (int i = 0; i != bytes.length; i++) {
            char ch = string.charAt(i);

            bytes[i] = (byte) ch;
        }

        return bytes;
    }

    public static int toByteArray(String s, byte[] buf, int off) {
        int count = s.length();
        for (int i = 0; i < count; ++i) {
            char c = s.charAt(i);
            buf[off + i] = (byte) c;
        }
        return count;
    }

    /**
     * Convert an array of 8 bit characters into a string.
     *
     * @param bytes 8 bit characters.
     * @return resulting String.
     */
    public static String fromByteArray(byte[] bytes) {
        return new String(asCharArray(bytes));
    }

    /**
     * Do a simple conversion of an array of 8 bit characters into a string.
     *
     * @param bytes 8 bit characters.
     * @return resulting String.
     */
    public static char[] asCharArray(byte[] bytes) {
        char[] chars = new char[bytes.length];

        for (int i = 0; i != chars.length; i++) {
            chars[i] = (char) (bytes[i] & 0xff);
        }

        return chars;
    }

    public static String[] split(String input, char delimiter) {
        List<String> v = new LinkedList<>();
        boolean moreTokens = true;
        String subString;

        while (moreTokens) {
            int tokenLocation = input.indexOf(delimiter);
            if (tokenLocation > 0) {
                subString = input.substring(0, tokenLocation);
                v.add(subString);
                input = input.substring(tokenLocation + 1);
            } else {
                moreTokens = false;
                v.add(input);
            }
        }

        String[] res = new String[v.size()];

        for (int i = 0; i != res.length; i++) {
            res[i] = v.get(i);
        }
        return res;
    }

    public static String joinAll(String delimiter, String[] src) {
        return src == null ? null : org.apache.commons.lang3.StringUtils.join(src, delimiter);
    }

    public static String joinAll(String delimiter, List<String> src) {
        return src == null
                ? null
                : org.apache.commons.lang3.StringUtils.join(src.toArray(new String[0]), delimiter);
    }
}
